Moving very fast with a whistling or buzzing sound; moving through the air or space at high speed.
From the imitative word 'whiz' (onomatopoeia—the word mimics the sound it describes). The '-ing' form makes it a verb. 'Whiz' entered English in the 1600s as an attempt to represent a fast sound.
Onomatopoeia words like 'whizz' are amazing—they're some of the most universal words across languages because they literally imitate sounds, so a whizz in English sounds almost the same as one in Japanese.
Complete word intelligence in one call. Free tier — 50 lookups/day.